1. Field of the Invention
This invention relates to apparatus and an associated method for energizing a remote station through energy transmitted in space and, more specifically, it relates to such a system wherein data with respect to an object of interest may be obtained by the remote station and transmitted to the base station upon interrogation by the base station.
2. Description of the Prior Art
It has long been known in various applications to monitor conditions of a physical system or a patient and provide information in the nature of real-time readouts of certain conditions. Such systems typically have been connected by a suitable wire to a source of electricity at the desired voltage such as line current or batteries.
It has also been known to provide such systems in the medical environment in respect of monitoring characteristics such as patient respiration, heart beat, electrocardiograms and temperature, for example. See, generally, U.S. Pat. Nos. 4,129,125; 4,308,870; 4,443,730; 4,889,131; and 5,335,551.
It has also been known in the medical environment to monitor physiological parameters by employing sensors, a battery powered system, and digital processing means to effect comparison between the measured conditions and stored values and displaying the results. See U.S. Pat. No. 4,356,825.
U.S. Pat. Nos. 5,230,342 and 5,586,555 disclose blood pressure monitors employing a pressurizable pressure transducing bladder with particular emphasis on measuring blood pressure in a supraorbital artery.
U.S. Pat. No. 4,576,179 discloses the use of a chest motion transducer and associated heart rate monitoring apparatus. Cooperating electronics are provided. Alarm means may be triggered under appropriate conditions of the individual being monitored or an indication that the battery voltage has fallen below a preset level. There is an allusion to making provision for short range radio transmission of the signals to remote monitoring stations. See also U.S. Pat. No. 5,022,402.
U.S. Pat. No. 4,494,553 discloses a battery powered respiratory and cardiac monitor wherein a pair of inductance coils are employed along with VHF/FM transmission of signals.
In spite of the foregoing known systems, there remains a need for a remote unit usable in various environments and at various distances from the base station which remote unit will be adapted to be remotely energized so as not to require hard wired systems or batteries on the remote unit. There is also lacking such systems wherein the remote unit may be miniaturized so as to have numerous potential uses.